Modular belts, e.g., flat top belts, are widely used for applications where food is transported in direct contact with the belts. Belts and equipment for such transport must be regularly cleaned in order to avoid contamination due to contact of the food with decomposed residual matter or bacteria. Cleanability is therefore an important requirement for modular belts and efforts have been made to improve cleaning, to reduce cleaning time, and to reduce costs associated with cleaning.
Modular belts are assembled from individual modules linked by hinges to form a conveyor belt. The modules are typically made from solid plastics with a smooth surface. The plastic material is selected from materials that are approved for direct contact with foodstuff. These types of plastic modules are normally well cleanable. The main problem associated with cleaning occurs in the hinge area where the individual modules are linked together. The hinge area typically has gaps where foodstuff penetrates and may become trapped. These deposits of residual food matter are difficult to remove. In addition, the cleaning problem is often made worse by sprockets that are driving the belt. The sprocket teeth may press the residual food matter into the hinge area where it can become trapped and difficult to remove.
A modular conveying belt used in the food industry is shown in U.S. Pat. No. 4,925,016. In order to drive the conveying belt, a transverse rib is arranged on the underside of the module bodies. The rib is disposed transverse to the conveying direction. The conveying belt is driven by a plurality of parallel, spaced-apart toothed drive wheels that have drive teeth that are positioned against the transverse ribs. Guide teeth are provided on the toothed drive wheel in addition to the drive teeth. The guide teeth engage in the gap between two adjacent link ends of interengaging modules and thus guide the modular conveying belt laterally. This conveying apparatus has the disadvantage that the toothed drive wheels have guide teeth in addition to the drive teeth. Also, the additional guide teeth make cleaning more difficult, and there is a risk of conveyable articles passing onto the underside of the conveying belt and being pressed by the guide teeth into the narrow interspace between two adjacent link ends.
An improved design has been proposed by U.S. Pat. No. Re 38,607, assigned to Habasit AG, the assignee of the present invention. Although the problem of the additional tracking teeth was eliminated and thus the cleanability improved, these sprockets still cover the hinge area and therefore may hinder the accessability of cleaning fluid to the hinge gaps. The contact of the hinges with the sprocket teeth is needed in order to allow the belt to be tracked by the sprocket. Also, the sprocket is kept aligned with a certain position of the belt so that the proper engagement of the sprocket teeth with the hinge structure is maintained. Accordingly, there is a need for an improved system that maintains proper sprocket engagement yet allows for exposure of the hinge area for cleaning.